need answer quickly

5. A church opens at 8:00am on Sunday. The number of visitors entering the church in a minute follows a Poisson distribution with a mean of 1.8. (a) What is the variance of the number of visitors entering the church in a minute. (b) Find the probability that 3 visitors entering the church in the first two minutes after the church opens. (c) At 8:00, only one door at the entrance of the church is opened. If in any two consecutive minutes, there are at least 4 visitors entering the church in each minute, then a second door will be opened. Find the probability that the second door is just opened three minutes after the church opens. (10 marks)